Lubricating oil additives

ABSTRACT

Improved stability of overbased phenates, particularly when formulated with overbased sulphonates, as well as improved foaming tendency and viscosity is obtained by treated the overbased phenate, either during or subsequent to the overbasing process, with from 0.1 to 10 wt. %, preferably 2 to 6 wt. %, of a carboxylic acid with a C 10  to C 24  unbranched segment, e.g. behenic acid.

This is a continuation, of application Ser. No. 896,572, filed Aug. 18,1986, which is a Continuation of application Ser. No. 492,474, filed May6, 1983, both now abandoned.

This invention relates to lubricating oil additives which have highbasicity, commonly known as overbased additives, and concentrates andlubricating oils containing them.

Many additive concentrates for lubricating oil compositions containingoverbased additives suffer from lack of stability giving rise tosedimentation. Also such additives have a tendency to give foamingproblems either during their manufacture, during formulation oflubricating oils containing them or during their use as lubricants. Wehave now found that the addition of certain carboxylic acids eitherduring preparation of the overbased additive or to the formed overbasedadditive results in reduced tendency to sedimentation, reduced foamingand also may result in a valuable reduction in viscosity of oilsolutions of the additive.

Some attempts have been made in the past to improve stability oflubricating oil compositions containing overbased detergent additives.U.S. Pat. No. 3714042 describes the addition of a high molecular weightaliphatic carboxylic acid or anhydride having at least 25 aliphaticcarbon atoms per carboxy group to a basic Group I or II metal,specifically calcium or magnesium sulphonate, sulphonate-carboxylate orcarboxylate complex to reduce tendency to foam and haze. The preferredacids are polyisobutenyl succinic acids having a molecular weight of 700to 5000. U.S. Pat. No. 3793201 discloses similar high molecular weightacids (with at least 30 carbon atoms) as solubility improvers incombination with metal salts, such as alkaline earth metal salts ofbridged phenols for oil-soluble basic magnesium salts of sulphonicand/or carboxylic acids. GB 1471934 discloses lubricating oilcompositions containing an overbased detergent additive to which isadded to improve foam stability a) a mono- or dicarboxylic acid orderivative having at least 30 carbon atoms or a reaction product of aphosphorus sulphide with a hydrocarbon and b) a dihydric alcohol orglycol having 2 to 4 carbon atoms, a di- or tri-(C₂ -C₄) glycol or anether alcohol having 2 to 10 carbon atoms: the combination of apolyisobutylene succinic acid and glycol is preferred. Under severeconditions none of these prior art treatments have been found totallysatisfactory.

Other treatments of overbased additives with acids have been described.U.S. Pat. No. 3410801 describes the treatment of overbased metalsulphonates, particularly alkaline earth metal sulphonates, with from 10to 150 weight % of a C₁₂ to C₂₂ fatty acid to give a friction modifieradditive for a lubricating oil. U.S. Pat. No. 3242079 discloses greasecompositions comprising an overbased alkaline earth metal sulphonate andfrom 1 to 80 weight % of an active hydrogen compound such as a loweraliphatic carboxylic acid defined as having less than 8 carbon atoms.U.S. Pat. No. 4328111 describes the addition of acidic compoundsincluding organic carboxylic acids to over-based metal sulphonates,phenates or mixtures thereof to improve the properties of the overbasedmaterial in lubricating oil compositions and to improve solventseparation from the overbased material. The organic carboxylic acids maybe straight or branched, saturated, unsaturated or aromatic andoptionally substituted. A ratio of basic compound to acidic compound of1.5 to 50:1, preferably 2 to 20:1 is disclosed.

Acids have also been incorporated into the reaction mixture from whichoverbased detergent additives are prepared. GB 1297150 described theformation of basic magnesium salts of organic acids in which thereaction mixture comprises certain proportions of an organic acid foroverbasing, such as an aromatic carboxylic or sulphonic acid, and aseparate aliphatic carboxylic acid or sulphonic acid capable ofoverbasing. U.S. Pat. No. 3671430 describes the preparation of a highalkalinity oil-soluble alkaline earth metal hydrocarbon sulphonate usingan alkaline earth metal sulphonate as the dispersant and a seconddispersant which may be inter alia a long chain hydrocarbonmonocarboxylic acid, dicarboxylic acid or anhydride with from 20 to 200carbon atoms in the chain. U.S. Pat. No. 4164472 also describes the useof a saturated or unsaturated fatty acid as a dispersant in preparing acalcium-containing dispersion in a non-volatile liquid. GB 1469289describes the use of at least 0.1 weight % of a C1 to C18 carboxylicacid or derivative thereof as a promoter in the formation of anoverbased magnesium detergent.

We have found that certain carboxylic acids having a long, straightunbranched hydrocarbyl segment have a surprising effect in improving theproperties of lubricating oil compositions containing overbaseddetergent additives when employed in relatively small amounts.

The present invention therefore provides an additive concentrate forincorporation in a lubricating oil composition comprising lubricatingoil, and from 10 to 90 wt% of an overbased alkaline earth metalhydrocarbyl sulphurized phenate which has been treated, either during orsubsequent to the overbasing process, with from 0.1 to 10 wt % (based onthe weight of the additive concentrate) of an acid of the formula:##STR1## (wherein R is a C₁₀ to C₂₄ unbranched alkyl or alkenyl group,and R' is hydrogen, a C₁ to C₄ alkyl group or a --CH₂ --COOH group) oran anhydride or a salt thereof.

The concentrate will typically contain from 10 to 90 wt %, preferablyfrom 30 to 90 wt %, of the overbased phenate, and usually comprises atleast 50 wt % of active materials in solution in the lubricating oil.

The lubricating oil can be any animal, vegetable or mineral oil, forexample ranging from petroleum oil to SAE 30, 40 or 50 lubricating oilgrades, castor oil, fish oils or oxidised mineral oil.

Alternatively the lubricating oil can be a synthetic ester lubricatingoil and these include diesters such as di-octyl adipate, di-octylsebacate, didecyl azelate, tridecyl adipate, didecyl succinate, didecylglutarate and mixtures thereof. Alternatively the synthetic ester can bea polyester such as that prepared by reacting polyhydric alcohols suchas trimethylol propane and pentaerythritol with monocarboxylic acidssuch as butyric acid to give the corresponding tri- and tetra-esters.Also complex esters may be used, such as those formed by esterificationreactions between a carboxylic acid, a glycol and an alcohol or amono-carboxylic acid.

Overbased alkaline earth metal sulphurized hydrocarbyl phenates or"overbased phenates" are high alkalinity alkaline earth sulphurisedhydrocarbyl phenates which contain metal base in excess of that requiredfor neutralisation of the sulphurised hydrocarbyl phenol. The overbasedphenates where the hydrocarbyl group(s) are alkyl group(s) arepreferred, and the preparation of overbased phenates will be describedin relation to these preferred phenates.

The starting alkyl phenol may contain one or more alkyl substituents.These may be branched or unbranched, and depending on the number ofsubstituents be C₁ to C₃₀, preferably C₉ to C₁₈ groups. Mixtures ofalkyl phenols with different alkyl substituents may be used.

The alkyl phenol may be sulphurized as a separate step before theoverbasing stage described hereinafter. This sulphurization may beaccomplished by reacting the alkyl phenol with sulphur chloride or byreaction with sulphur in the presence of a base. Alternatively, thereaction with sulphur may be carried out as part of the overalloverbasing process. In addition to the desired sulphurised alkyl phenolof the general formula: ##STR2## (where x is an integer from 1 to 3, nis an integer from 1 to 3, R₁ is a C₁ -C₃₀ alkyl group, for example a C₉-C₁₈ alkyl group and R₂ is hydrogen or said alkyl group), the productmay contain a minor amount (typically 10 wt. % or less of thesulphurized alkyl phenol) of a number of byproducts resulting from sidereactions, e.g. chlorination of the aromatic ring when using sulphurchloride, or formation of organo sulphur groups resulting from reactionof sulphur with overbasing reaction solvents.

The sulphurised alkyl phenol is reacted with excess alkaline earth metalbase in the presence of a dihydroxyl solvent which is usually ethyleneglycol although other glycols may be used. An additional monohydroxylsolvent (e.g. isodecanol) may also be used. The alkaline earth metalbase may be an oxide or a hydroxide. Carbon dioxide is then introducedto convert the excess metal base into metal carbonate. Volatile reactionproducts and solvents are then removed by distillation filtration orcentrifugation. Alternatively, as indicated above, sulphur and alkylmetal may be charged prior to carbonation to form the sulphurised phenolin situ, which is then reacted with base and carbonated as described. Asan alternative a metal alkoxide may be used as the starting metal baseand the inclusion of water is then required to hydrolyse the alkoxides.For this modification, glycol esters are suitable solvents. A carbonatedmetal alkoxide can also be used.

Highly preferred overbased phenates are the overbased calcium phenatesand overbased magnesium phenates. A preferred process for preparation ofoverbased calcium phenate is described in GB 1 470 338. A preferredprocess for preparation of overbased magnesium phenate is described inGB 1 469 289.

The acid of general formula I may be a mono- or dicarboxylic acidprovided that it has a long, unbranched alkyl or alkenyl segment. When Ris an alkenyl group it preferably contains only one double bond, andalkyl groups are most preferred.

A preferred group of acids of general formula I are those wherein R is aC₁₀ to C₂₄ straight chain alkyl group and R' is hydrogen. A particularlypreferred group of acids of general formula I are unbranched, saturatedfatty acids having from 12 to 24 carbon atoms, most preferably from 18to 24 carbon atoms. Examples include lauric, myristic, palmitic,stearic, eiconsanoic and behenic acid. The fatty acids need not be pure,and commercial grades containing a range of fatty acids, including someunsaturated components, are acceptable. Mixed fatty acids such as thosederived from linseed oil, soybean oil and tall oil may also be used.

An example of a preferred unsaturated acid, especially for use intreating the overbased phenate subsequent to the overbasing process, isoleic acid.

Synthetic mono- and dicarboxylic acids may be used, and these may beprepared by functionalising an appropriate straight chain α-olefin, forexample by reaction with an appropriate anhydride. Dicarboxylic acidsmay be obtained by reaction of the α-olefin with maleic anhydride.

Anhydrides and salts of these acids may be employed. The choice of asalt for use in the invention should be chosen having regard to theother components of the additive and the point at which it is to beadded. Generally metal salts corresponding to the metal in the overbasedsulphurized phenate are preferred, provided that they are compatiblewith the other components under the conditions at which they areintroduced.

The acid or derivative is employed in an amount of from 0.1 to 10 weight% based on the weight of the additive concentrate, and preferably from 2to 6 weight % acid or derivative thereof is employed.

As an example stearic acid may be added to the reaction mixture forpreparing an overbased calcium sulphurized phenate prior to carbonationin an amount of 2 to 6 weight % stearic acid, based on the weight of theresultant additive concentrate containing the overbased product. Thishas been found to give improved foam and sediment performance togetherwith an improvement in viscosity.

The acid may be used in addition to other compounds conventionallyemployed to enhance the properties of overbased detergent additives. Inparticular, it may be used in conjunction with the treatment of theoverbased additive with the high molecular weight acid and glycolcombination described in GB 1 471 934.

It has been found most surprisingly that particularly good results areobtained by using the acid treatment of the invention in conjunctionwith the addition to the overbased phenate of certain glycols and etherderivatives thereof.

The invention extends to a process for preparing an additive concentratecomprising adding to a lubricating oil an overbased alkaline earth metalsulphurized phenate and at least 0.1 weight % (based on the weight ofthe total additive concentrate) of an acid of general formula I, or ananhydride or salt thereof. The acid of general formula I or itsderivative is preferably introduced at a temperature of from 20° to 210°C., more preferably from 80° to 150° C. The temperature is chosen toensure adequate fluidity and to enable ready mixing with the othercomponents of the additive concentrate. Alternatively, the inventionprovides a process in which an acid of general formula I or an anhydrideor salt thereof is introduced into a reaction mixture for preparing anoverbased alkaline earth metal sulphurized phenate and containing alubricating oil to form the desired concentrates of the invention. Inthis alternative process the acid may be added to the overbasingreaction mixture in addition to conventional additives to thatoverbasing process such as organic sulphonic acids, sulphonates orsulphates and reaction promoters such as C₁ to C₄ acids or theirderivatives e.g. salts of formic acid.

In a preferred aspect there is added to the additive concentrate of theinvention at least 0.1 wt % (based on the weight of the additiveconcentrate) of a polyhydric alcohol having from 2 to 4 carbon atoms, adi- or tri- (C₂ -C₄) glycol or an ether alcohol having from 2 to 10carbon atoms. The polyhydric alcohol may, for example, be a dihydricalcohol such as ethylene glycol or propylene glycol or a trihydricalcohol such as glycerol. Examples of di- and triglycols includediethylene glycol and triethylene glycol. Examples of ether alcoholsinclude the alkyl ethers of the previously mentioned glycols. Thepreferred glycol is ethylene glycol.

It has been found advantageous to add from 0.1 to 10 wt % (based on theweight of the additive concentrate) of the glycol or ether derivativethereof and from 0.5 to 6 wt % is preferred. The glycol or etherderivative thereof is added to the additive concentrate subsequent tothe overbasing process. As indicated hereinbefore it is usual to employa solvent such as ethylene glycol in the overbasing process and this isthen removed, most usually by distillation or stripping. The glycol orether derivative thereof may be added to the additive concentratesubsequent to the step of removing any solvent and volatile material.When the acid of general formula I or its derivative is also added tothe overbased phenate subsequent to the overbasing process the acid andglycol may be added separately in either order or together. In apreferred aspect of the alternative process when the acid is added tothe overbasing reaction mixture, the glycol or ether derivative thereofis added to the additive concentrate subsequent to the overbasingreaction.

The additive concentrates of the invention may also be combined withother lubricating oil additives and concentrates to form a lubricatingoil additive package or a complete lubricating oil, e.g. withdispersants, viscosity index improvers, anti-oxidants, anti-wearadditives and lubricity improvers.

Such additive packages will typically contain from 10 to 90 wt. % ofactive materials, and generally contain at least 50 wt. % of activematerial. The amount of overbased sulphurized phenate treated with acidaccording to the invention which is incorporated within such packagesmay vary within very wide limits depending on the end-use for which thepackage is intended and the amount of other additives.

The invention extends to lubricating oil compositions comprisinglubricating oil and from 0.01 to 30 wt. % (based on the totalcomposition) of an additive concentrate of the invention comprising from10 to 90 wt % of the overbased alkaline earth metal hydrocarbylsulphurized phenate optionally with other additives as describedhereinbefore. Preferably lubricating oil compositions contain from 0.5to 20 wt. % of the additive concentrate.

The invention will now be further described, though only by way ofillustration, with reference to the following Examples.

In the following Examples, the performance of additive concentrates ofthe invention is evaluated in terms of their foaming tendency, viscosityand stability with other additives, and their performance is comparedwith that of a conventional overbased additive concentrate, alone andwith conventional supplements to improve foam and stability performance.In the first series of Examples the conventional overbased additiveconcentrate is an oil solution of an overbased calcium sulphurized alkylphenate prepared from dodecyl phenol containing 3.63%S and 10.4%Ca with272 TBN (Total Base Number--ASTM D664), and approximately 27 weight %oil--it is referred to hereinafter as "additive concentrate X".

Foam tendency

The foaming tendency of the additive concentrate is measured accordingto standard method ASTM D892-74 (IP 146/73) in which a 2 wt % solutionof the sample under test in a base oil is blown with air at a constantrate for five minutes and allowed to settle for ten minutes, with thefoam volume being measured in ml at the end of both periods. The resultsare given as two numbers, the first representing the foam volume afterten minutes settling. This test is also carried out with the addition of400 ppm of a conventional silicone anti-foaming additive.

Kinematic Viscosity

Viscosity of the additive concentrate is measured at 100° C. usingstandard method ASTM D445-79 (IP71/79). The results are given in cSt.(1m² /s=10⁴ St).

Stability

Stability is measured by blending 19.8 weight % of the additiveconcentrate under test with 80.2 weight % of a heavy paraffinic base oilcontaining an overbased calcium salt of a branched chain C₂₄ sulphonicacid with 300 TBN and other overbased detergent additives such that theblend has an overall TBN of 70. The blend is made at 70° C., then pouredinto a 100 ml centrifuge tube and stored at room temperature(approximately 20° C.). Volume % sediment is observed at initialformulation and after three weeks. This blend, containing both overbasedphenate and overbased sulphonates has been found to present particularproblems of compatibility, and thus to be an extremely severe test ofthe additive concentrates of the invention.

EXAMPLES 1-7: POST-TREATMENT OF OVERBASED CALCIUM PHENATES

Samples of the additive concentrate X are mixed with various fatty acidsat 110° C. to form additive concentrates of the invention, which aretested as described above. To provide a comparison, tests were alsocarried out on additive concentrate X alone, and with the addition ofPIBSA (polyisobutylene succinic acid, M.W. approx. 900) and ethyleneglycol. The results are given in Table 1, and show that the compositionsof the invention give improved stability and foam performance, withreduced viscosity as compared to the untreated comparison and thecomparison samples treated with PIBSA alone and ethylene glycol alone.The compositions also appear to be more readily controlled by theaddition of conventional silicone anti-foam additives. The comparisonsample treated with a PIBSA/ethylene glycol combination show goodfoaming performance when treated with a silicone additive but has ahigher viscosity than most of the compositions of the invention andshowed poorer stability after 3 weeks.

                                      TABLE 1                                     __________________________________________________________________________                       Foam tendency (ml/ml)                                                                          Stability                                                         with 400 ppm                                                                         Viscosity                                                                          (% sediment)                              Example                                                                              Treatment                                                                             wt. %    silicone                                                                             (cSt)                                                                              Initial                                                                           3 weeks                               __________________________________________________________________________    Comparison                                                                           None    --  510/460                                                                            370/360                                                                              622  hazy                                                                              n.m.*                                 "      PIBSA   2.5 430/390                                                                            580/260                                                                              915  hazy                                                                              n.m.                                  "      ethylene glycol                                                                       2.5 640/570                                                                            480/230                                                                              n.m. hazy                                                                              n.m.                                  "      PIBSA + 2.0 +                                                                             600/530                                                                            0/0    424  clear                                                                             6                                            ethylene glycol                                                                       2.0                                                            1      stearic acid                                                                          5.0  70/40                                                                             0/0    244  clear                                                                             1                                     2      behenic acid                                                                          5.0 220/30                                                                             0/0    290  clear                                                                             0                                     3      Prifac 2989.sup.1                                                                     5.0 430/80                                                                             0/0    339  clear                                                                             0                                     4      behenic acid.sup.2                                                                    5.0 410/60                                                                             0/0    267  clear                                                                             0                                     5      oleic acid                                                                            5.0 380/350                                                                            0/0    250  clear                                                                             2                                     6      behenic acid +                                                                        3.0 +                                                                             470/180                                                                            0/0    436  clear                                                                             0                                            ethylene glycol                                                                       3.0                                                            7      behenic acid +                                                                        2.0 +                                                                             770/690                                                                            350/210                                                                              278  clear                                                                             0                                            sulphonic acid.sup.3                                                                  5.0                                                            __________________________________________________________________________     Notes.                                                                        *n.m. = not marked                                                            .sup.1 Product of Unichemna International  87% behenic acid, iodine value     2.0                                                                           .sup.2 Product of Henkel & Cie GmbH  80% behenic acid                         .sup.3 Alkyl benzene sulphonic acid  80% C.sub.24 --20% C.sub.18         

Example 8: Preparation of overbased calcium sulphurized phenate usingbehenic acid

An additive concentrate of the invention was prepared by adding behenicacid prior to carbonation in the synthesis of additive concentrate X. Areaction mixture was prepared from:

230 g (0.88 moles) dodecylphenol

40 g (0.12 moles) behenic acid

63 g (1.97 moles) sulphur

135 g (0.85 moles) isodecanol

95 g (1.70 moles) calcium oxide

and stirred at 70° C. A mixture of 162 g (2.61 moles) ethylene glycoland 6.7 g (0.37 moles) water was added dropwise over 30 minutes. Thetemperature was increased to 110° C. 108 g of a lubricating oil wereadded and carbonation was commenced by introducing 50 ml/min. carbondioxide. The temperature was increased to 150° C. over 1 hour, thenfurther increased to 160° C. over 40 minutes, and to 170° C. over afurther 20 minutes. Carbonation was continued for about 6 hours untilthe end point was reached. Then carbonation was stopped and thetemperature raised to 210° C., finally stripping at 60 mm Hg absolutepressure to remove solvent. The vacuum was released, 67 g of base oilwere added and the whole cooled to 170° C. After filtration acomposition containing an overbased calcium sulphurized phenate andapproximately 6 weight % (based on the weight of the concentrate)behenic acid was obtained. TBN was 244, calcium content 10.1 weight %and sulphur content 3.85 weight %. This was tested as described aboveand the following results obtained:

    ______________________________________                                        Kinematic Viscosity (100° C.)                                                               399 cSt                                                  Foam (ml)            0/0                                                      Stability after 3 weeks                                                                            clear (0% sediment)                                      ______________________________________                                    

To provide a comparison a similar overbased calcium sulphurized phenatewas prepared without behenic acid from the following reaction mixture:

    ______________________________________                                        270 g             dodecylphenol                                                63 g             sulphur                                                     135 g             isodecanol                                                   95 g             calcium oxide                                               ______________________________________                                    

using the procedure described above. The product had a TBN of 262 andcontained 10.15 wt. % calcium and 3.84 wt. % sulphur. This was tested asdescribed above and the following results obtained:

    ______________________________________                                        Kinematic Viscosity (100° C.)                                                                 956 cSt                                                Foam (ml)              560/500                                                Stability              Initially hazy                                         ______________________________________                                    

This clearly shows the advantage of the additive concentrate of theinvention over a prior art concentrate prepared without the use ofbehenic acid. The concentrate of the invention gave excellent resultswith perfect results in the foam test as compared to a considerablefoaming tendency found when behenic acid was not used. The concentrateof the invention was initially clear and remained a clear solution after3 weeks in the stability test. The decreased viscosity of theconcentrate of the invention is also an important credit.

Examples 9-21: Preparation of overbased calcium sulphurized phenate inthe presence of acid

The procedure of Example 8 was repeated using different amounts ofvarious acids, and in some cases with the addition of ethylene glycolsubsequent to overbasing. The foam performance and stability of theproducts was tested as described hereinbefore, with the exceptions thata) the foam test was carried out on a 1.8 wt % solution of the sample ina lubricating oil formulated without an overbased phenate but containingthe remainder of the additives chosen for the finished oil and b) thestability test was carried out over 4 weeks at 20° C. and 60° C. Toprovide a comparison the same testing was carried out on additiveconcentrate X alone and on additive concentrate X to which had beenadded 2.0 wt % PIBSA (M.W.=900) and 2.0 wt % ethylene glycol. Theresults are given in Table 2, and show the significant improvement infoam and stability performance for the additive of the invention againstthe untreated additive X and additive X post-treated with PIBSA/glycol.Moreover, the improvement is achieved with a valuable decrease inviscosity whereas the PIBSA/glycol treatment results in a viscosityincrease.

                                      TABLE 2                                     __________________________________________________________________________                          Foam Tendency                                                                 (ml/ml)         Stability (%)                                                      +400 ppm                                                                            Viscosity                                                                          4 weeks                                                                             4 weeks                           Example                                                                              Treatment                                                                             (wt %)                                                                            TBN     silicone                                                                            (cSt)                                                                              at 20° C.                                                                    at 60° C.                  __________________________________________________________________________    Comparison                                                                           None    --  254                                                                              620/560                                                                            480/380                                                                             417  15    3                                        PIBSA + 2.0 +                                                                             256                                                                              520/550                                                                            50/0  640  3     1.8                                      ethylene glycol                                                                       2.0                                                            9      stearic acid                                                                          5.0 249                                                                              550/500                                                                            0/0   347  0/1   0.075                             10     stearic acid                                                                          4.0 236                                                                              470/430                                                                            0/0   198  (2% haze)                                                                           0.45                              11     stearic acid +                                                                        4.0 +                                                                             244                                                                              520/460                                                                            0/0   278  (1% haze)                                                                           0.025                                    ethylene glycol.sup.1                                                                 1.0                                                            12     stearic acid                                                                          3.0 253                                                                              430/420                                                                            50/0  254  1.0   0.25                              13     stearic acid +                                                                        3.0 +                                                                             250                                                                              460/410                                                                            0/0   278  0.03  0.08                                     ethylene glycol.sup.1                                                                 1.0                                                            14     stearic acid +                                                                        3.0 +                                                                             246                                                                              470/390                                                                            0/0   232  0     trace                                    ethylene glycol                                                                       2.0                                                            15     stearic acid +                                                                        3.0 +                                                                             249                                                                              410/350                                                                            0/0   411  0     0                                        ethylene glycol                                                                       3.0                                                            16     behenic acid                                                                          5.0 244                                                                              400/70                                                                             0/0   568  0     0                                 17     behenic acid                                                                          4.0 248                                                                              530/450                                                                            0/0   557  haze  0.2                               18     behenic acid +                                                                        4.0 +                                                                             248                                                                              490/470                                                                            0/0   585  very  0                                        ethylene glycol.sup.1                                                                 1.0                    slight haze                             19     behenic acid                                                                          3.0 248                                                                              700/630                                                                            70/0  577  6     0.9                               20     behenic acid +                                                                        3.0 +                                                                             249                                                                              500/440                                                                            0/0   628  trace 0.025                                    ethylene glycol.sup.1                                                  21     behenic acid +                                                                        3.0 +                                                                             247                                                                              640/580                                                                            0/0   752  trace 0                                        ethylene glycol.sup.1                                                  __________________________________________________________________________     .sup.1 addition of ethylene glycol to additive concentrate               

Example 22: Preparation overbased calcium sulphurized phenate in thepresence of stearic acid

The procedure of Example 14 was repeated replacing ethylene glycol by 2wt % of glycerol. The resulting product when treated with 400 ppmsilicone had a foam tendency of 70/0.

Example 23: Treatment of overbased sulphurized magnesium phenates

A further series of tests was carried out on a conventional additiveconcentrate comprising an oil solution of an overbased magnesiumsulphurized phenate containing 5.4 wt. % magnesium and 3.8 wt. % sulphurwith a TBN of 245.

This was prepared as follows:

320 g of a 90% oil solution of sulphurized nonyl phenol having a minimumhydroxy number of 207 and containing 9 wt. % sulphur was mixed with 270g of oil 583 g of magnesium ethoxide was added under a nitrogen blanket.A mixture of 64 g of ethoxyethanol and 64 g of water were added over 1hour at 80° C. The mixture was then carbonated at 80° C. to 102° C. over2 hours then during further carbonation held at 102° C. and finallyheated to 150° C. for a total carbonation time of 8.5 hours during which40-45 g of carbon dioxide were added. 106 g of oil were added and themixture was stripped to yield the product. This additive concentrate wastested for foam tendency alone and with silicone anti-foaming additives.It was also converted to an additive concentrate of the invention by theaddition of 5 wt. % (based on the weight of the additive concentrate) ofbehenic acid.

                  TABLE 3                                                         ______________________________________                                        Treatment        Foam Tendency                                                Example Acid     wt. %          with 400 ppm silicone                         ______________________________________                                        Comparion                                                                             None     --      540/490                                                                              560/520                                       14      behenic  5       40/0   0/0                                                   acid                                                                  ______________________________________                                    

The untreated additive gave poor foam performance which was not improvedby addition of a silicone anti-foam additive. By contrast addition ofbehenic acid to the additive concentrate resulted in a product withexcellent foam performance even without addition of silicone.

Examples 24-26: Preparation of overbased sulphurized magnesium phenatein the presence of acid

29.4 kg of a 72% oil solution of sulphurized nonyl phenol having aminimum hydroxy number of 130 and containing 7 wt % sulphur was mixedwith 6.3 kg of oil and 2.3 kg of crude behenic acid (55% behenic, 35%C₂₀, 7% stearic and 3% other acids) were mixed. 37.7 kg of magnesiumethoxide was added under a nitrogen blanket. A mixture of 3.8 kg ofcellosolve and 3.8 kg of water were added over 1 hour at 80° C. Themixture was then carbonated at 80° C. to 100° C. over 2 hours thenduring further carbonation held at 100° C. and finally heated to 150° C.for a total carbonation time of 8.5 hours during which 7.1 kg of carbondioxide are added 3.4 kg of oil were added and the mixture was strippedto yield a product of 235 TBN at 5.4 wt % Mg with 4.0% acid.

A generally similar procedure was carried out to prepare additiveconcentrates containing stearic acid (prepared from commercial acidcontaining 94.9 wt % stearic, 1.4 wt % C₁₆, 2.3 wt % C₁₉, 0.3 wt % C₁₉,0.9 wt % C₂₀).

The foaming tendency of these products was measured as a 2% solution inthe oil used for foam testing in Examples 1 to 7 and as a 2% solution ina high foaming base oil. The results given in Table 4 below showexcellent foam performance even in a high foaming oil when compared tothe comparison in Example 23.

                  TABLE 4                                                         ______________________________________                                                       Foam tendency                                                                 (ml/ml)                                                                       (no silicone addition)                                         Example                                                                              Treatment (wt %)       high foaming oil                                                                        Viscosity                             ______________________________________                                        24     crude     4.0     0/0  0/0       262                                          behenic                                                                       acid                                                                   25     stearic acid                                                                            3.0     0/0  350/250   226                                   26     stearic acid                                                                            5.0     0/0  40/0      194                                   ______________________________________                                    

We claim:
 1. An additive concentrate for incorporation in lubricatingoil composition consisting essentially of lubricating oil; and from 10to 90 wt. % of overbased alkaline earth metal hydrocarbyl sulphurizedphenate which has been treated, either during or subsequent tooverbasing, with from 0.1 to 10 weight %, based on the weight of theadditive concentrate, of stearic acid or anhydride or salt thereof, andwhich has a total base number of 235-.[.300.]. .Iadd.about 260.Iaddend..2. An additive concentrate as claimed in claim 1, which contains from 30to 90 wt. % of the overbased phenate.
 3. An additive concentrate asclaimed in claim 1, in which the overbased phenate is an overbasedalkaline earth metal sulphurized alkyl phenate comprising C₉ to C₁₈alkyl groups.
 4. An additive concentrate as claimed in claim 1, in whichthe overbased phenate is an overbased calcium phenate or an overbasedmagnesium phenate.
 5. An additive concentrate as claimed in claim 1, inwhich from 2 to 6 weight % of the acid or anhydride or salt thereof, isemployed.
 6. An additive concentrate for incorporation in a lubricatingoil composition consisting essentially of lubricating oil; from 10 to 90wt. % of overbased alkaline earth metal hydrocarbyl sulphurized phenatewhich has been treated, either during or subsequent to overbasing, withfrom 0.1 to 10 weight % of stearic acid or anhydride or salt thereof,and which has a total base number of 235-.[.300.]. .Iadd.about 260.Iaddend.and at least 0.1 wt. % of material selected from the groupconsisting of polyhydric alcohol having from 2 to 4 carbon atoms, di- ortri- (C₂ -C₄) glycol and ether alcohol having from 2 to 10 carbon atoms.7. A process for preparing an improved additive concentrate consistingessentially of adding to lubricating oil from 10 to 90 wt. %, based onthe weight of the total additive concentrate, of overbased alkalineearth metal hydrocarbyl sulphurized phenate having a total base numberof 235-.[.300.]. .Iadd.about 260.Iaddend., and from 0.1 to 10 weight %,based on the weight of the total additive concentrate, of stearic acidor anhydride or salt thereof, wherein said concentrate is improved in atleast one of reduced tendency to sedimentation, reduced foaming andreduced viscosity.
 8. A process as claimed in claim 7, in which the acidor anhydride or salt thereof is introduced at a temperature of from 20°C. to 210° C.
 9. A process as claimed in claim 8, in which thetemperature is from 80° C. to 140° C.
 10. A process for preparingimproved additive concentrate consisting essentially of adding tolubricating oil from 10 to 90 wt. % of overbased alkaline earth metalhydrocarbyl sulphurized phenate having a total base number of235-.[.300.]. .Iadd.about 260.Iaddend., from 0.1 to 10 weight % ofstearic acid or anhydride or salt thereof; and at least 0.1 wt. % ofmaterial selected from the group consisting of polyhydric alcoholcontaining from 2 to 4 carbon atoms, di- or tri- (C₂ -C₄) glycol orether alcohol having from 2 to 10 carbon atoms, wherein said concentrateis improved in at least one of tendency to sedimentation, foaming andviscosity.
 11. A lubricating oil composition comprising from 0.01 to 30wt. %, based on the total composition weight, of additive concentrate insolution in lubricating oil, the additive concentrate consistingessentially of lubricating oil, and from 10 to 90 wt. % of an overbasedalkaline earth metal hydrocarbyl sulphurized phenate which has beentreated, either during or subsequent to the overbasing process, withfrom 0.1 to 10 wt. %, based on the weight of the additive concentrate,of stearic acid or anhydride or salt thereof, and which has a total basenumber of 235-.[.300.]. .Iadd.about 260.Iaddend..
 12. A composition asclaimed in claim 11, which contains from 0.5 to 20 wt. % of the additiveconcentrate.
 13. A method for reducing the viscosity of an additiveconcentrate consisting essentially of lubricating oil and from 10 to 90wt. % of overbased alkaline earth metal hydrocarbyl sulphurized phenatehaving a total base number of 235-.[.300.]. .Iadd.about 260.Iaddend.consisting essentially of treating the phenate, either duringor subsequent to overbasing, with from 0.1 to 10 wt. %, based on theweight of the additive concentrate, of stearic acid or anhydride or saltthereof.
 14. A method according to claim 13, wherein said alkaline earthmetal is selected from the group consisting of calcium and magnesium;and wherein said hydrocarbyl is C₈ to C₁₈ alkyl group. .Iadd.
 15. Anadditive concentrate for incorporation in lubricating oil compositionconsisting essentially of lubricating oil; and from 10 to 90 wt. % ofoverbased alkaline earth metal hydrocarbyl sulphurized phenate which hasbeen treated, either during or subsequent to overbasing, with from 0.1to 10 weight %, based on the weight of the additive concentrate, ofstearic acid or anhydride or salt thereof, and having a total basenumber of at least
 235. .Iaddend..Iadd.16. An additive concentrate asclaimed in claim 15, which contains from 30 to 90 wt. % of the overbasedphenate. .Iaddend..Iadd.17. An additive concentrate as claimed in claim15, in which the overbased phenate is an overbased alkaline earth metalsulphurized alkyl phenate comprising C₉ to C₁₈ alkyl groups..Iaddend..Iadd.18. An additive concentrate as claimed in claim 15, inwhich the overbased phenate is an overbased calcium phenate or anoverbased magnesium phenate. .Iaddend..Iadd.19. An additive concentrateas claimed in claim 15, in which from 2 to 6 weight % of the acid oranhydride or salt thereof, is employed. .Iaddend..Iadd.20. An additiveconcentrate for incorporation in a lubricating oil compositionconsisting essentially of lubricating oil; from 10 to 90 wt. % ofoverbased alkaline earth metal hydrocarbyl sulphurized phenate which hasbeen treated, either during or subsequent to overbasing, with from 0.1to 10 weight % of stearic acid or anhydride or salt thereof, and havinga total base number of at least 235; and at least 0.1 wt. % of materialselected from the group consisting of polyhydric alcohol having from 2to 4 carbon atoms, di- or tri-(C₂ -C₄) glycol and ether alcohol havingfrom 2 to 10 carbon atoms. .Iaddend..Iadd.21. A process for preparing animproved additive concentrate consisting essentially of adding tolubricating oil from 10 to 90 wt. %, based on the weight of the totaladditive concentrate, of overbased alkaline earth metal hydrocarbylsulphurized phenate having a total base number of at least 235, and from0.1 to 10 weight %, based on the weight of the total additiveconcentrate, of stearic acid or anhydride or salt thereof, wherein saidconcentrate is improved in at least one of reduced tendency tosedimentation, reduced foaming and reduced viscosity. .Iaddend..Iadd.22.A process as claimed in claim 21, in which the acid or anhydride or saltthereof is introduced at a temperature of from 20° C. to 210° C..Iaddend..Iadd.23. A process as claimed in claim 22, in which thetemperature is from 80° C. to 140° C. .Iaddend..Iadd.24. A process forpreparing improved additive concentrate consisting essentially of addingto lubricating oil from 10 to 90 wt. % of overbased alkaline earth metalhydrocarbyl sulphurized phenate having a total base number of at least235; from 0.1 to 10 weight % of stearic acid or anhydride or saltthereof; and at least 0.1 wt. % of material selected from the groupconsisting of polyhydric alcohol containing from 2 to 4 carbon atoms,di- or tri- (C₂ -C₄) glycol or ether alcohol having from 2 to 10 carbonatoms, wherein said concentrate is improved in at least one of tendencyto sedimentation, foaming and viscosity. .Iaddend..Iadd.25. Alubricating oil composition comprising from 0.01 to 30 wt. %, based onthe total composition weight, of additive concentrate in solution inlubricating oil, the additive concentrate consisting essentially oflubricating oil, and from 10 to 90 wt. % of an overbased alkaline earthmetal hydrocarbyl sulphurized phenate which has been treated, eitherduring or subsequent to the overbasing process, with from 0.1 to 10 wt.%, based on the weight of the additive concentrate, of stearic acid oranhydride or salt thereof, and having a total base number of at least235. .Iaddend..Iadd.26. A composition as claimed in claim 25, whichcontains from 0.5 to 20 wt. % of the additive concentrate..Iaddend..Iadd.27. A method for reducing the viscosity of an additiveconcentrate consisting essentially of lubricating oil and from 10 to 90wt. % of overbased alkaline earth metal hydrocarbyl sulphurized phenatehaving a total base number of at least 235 consisting essentially oftreating the phenate, either during or subsequent to overbasing, withfrom 0.1 to 10 wt. %, based on the weight of the additive concentrate,of stearic acid or anhydride or salt thereof. .Iaddend..Iadd.28. Amethod according to claim 27, wherein said alkaline earth metal isselected form the group consisting of calcium and magnesium; and whereinsaid hydrocarbyl is C₂ to C₁₈ alkyl group. .Iaddend.